The invention relates to a method and an apparatus for the start-up operation of a multi-axis system.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Multi-axis systems are universal, programmable machines for handling, assembling or machining workpieces. They are also referred to as (industrial) robots. They are designed for use in the industrial field. Once such a multi-axis system is programmed, it is capable of autonomously performing a work sequence or of varying, within limits, the performance of a task in dependence on sensor information.
The risks such multi-axis systems pose are due to the complex movement patterns and the great accelerations with simultaneously enormous forces that are frequently completely unpredictable for a person. Working beside an unsafe multi-axis system could therefore quickly result in severe injuries for a person located near the multi-axis system.
In order to prevent such accidents, safe monitoring of the position, position-dependent monitoring of the speed, of an acceleration and of the orientation of moving components of the multi-axis system are necessary. This is true in particular for work environments in which a multi-axis system is to cooperate with a person.
One prerequisite for the correct and safe function of such a multi-axis system is the definition of bounding bodies for the moving components and the correct definition of safe spaces and workspaces. Bounding bodies can have different geometric dimensions and shapes. Typically used bounding bodies are e.g. spheres, boxes or structures composed of a plurality of boxes. The definition of bounding bodies and the determination of safe spaces and workspaces permits cooperation between a multi-axis system and people, as long as it is certain that no bounding body of a component of the multi-axis system penetrates a safe space. If mistakes are made when defining these bodies, e.g. penetration of a bounding body into a safe space during running operation is not recognized, and therefore a safety function is erroneously not triggered.
Manually inputting coordinates, dimensions and orientation of the bounding bodies of the components of a multi-axis system into a program or database is known. In addition to a high manual effort, this procedure has the disadvantage that checking of the bounding bodies that are obtained from the input is susceptible to errors in reasoning and input. Another known possibility is that of defining safe spaces by moving the tool of the multi-axis system to the corners of all non-moving bodies, i.e. of the safe spaces and the workspace, while simultaneously capturing and storing corresponding coordinates. However, this variant is suitable only for bounding bodies of non-moving spaces, but not for bounding bodies of moving components of the multi-axis system.
Both above approaches operate in “point-orientated” fashion. A user defining the bounding bodies must therefore compose the bounding bodies in his or her mind from a plurality of points in the three-dimensional space. This requires great cognitive power and is therefore susceptible to errors. Moreover, it is not easy to identify whether a bounding body of a segment of the multi-axis system in fact actually completely contains said segment. A further problem is that it is impossible to readily determine whether a defined bounding body has been assigned to the correct segment of the kinematics of the multi-axis system. If this is not the case, said bounding body may in fact be located at the correct segment in the rest state, but upon movement follows e.g. another segment, and not the segment that is actually assigned to it.
It would be desirable and advantageous to provide an improved method and apparatus to obviate prior art shortcomings and to reliably permit start-up operation of a multi-axis system in computer-supported fashion.